Carburetor

ABSTRACT

A carburetor for an internal combustion engine comprises a housing, porous matter contained in the housing, means for injecting fuel into the housing and onto the porous matter to effect completion of vaporization of the fuel, means for admitting air into the housing to form a mixture with the vaporized fuel and means for conducting the mixture out of the housing for combustion in the engine. Preferably, means are provided for transferring heat from the exhaust gases of the engine to the housing and the porous matter and to the fuel before the fuel is injected into the housing.

REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of application Ser. No. 806,798, filedJune 15, 1977, which, in turn, is a continuation-in-part of applicationSer. No. 770,964, filed Feb. 22, 1977.

BACKGROUND OF THE INVENTION

This invention relates to a novel carburetor for an internal combustionengine.

There is a great demand for motor vehicle internal combustion engineswhich will consume fuel more efficiently, resulting in greater mileage(miles per gallon) and less exhaust of hydrocarbons. Moreover, enginesof lower initial cost are very much wanted.

It is an object of this invention to provide an improved internalcombustion engine carburetor which is very much simpler and lessexpensive than prior art carburetors and which results in more efficientfuel consumption with consequent greater mileage and less exhaust ofhydrocarbons.

Other objects and advantages of the invention will be apparent from thefollowing description.

SUMMARY OF THE INVENTION

According to the invention, there is provided an improved carburetorwhich insures sufficient heating of the fuel and the mixture of fuel andair so that the fuel will be completely vaporized before entering theintake manifold of the engine.

The carburetor of the invention comprises a housing, porous mattercontained in the housing, the porous matter being inert relative to thefuel for the engine, means for injecting fuel into the housing and ontothe porous matter to effect completion of vaporization of the fuel,means for admitting air into the housing simultaneously with theinjection of the fuel to form a mixture with the vaporized fuel andmeans for conducting the mixture out of the housing for combustion inthe engine. The term "carburetor" as used herein means apparatus thatforms a mixture of vaporized fuel and air. It is readily seen from thedescription of the invention herein that this is not a conventional"carburetor" in the sense in which that term is more commonly used andin which fuel is atomized in a stream of air with the assistance of aventuri. The porous matter is typically a porous mineral or refractorymaterial such as porous (unglazed) ceramic, broken up brick, cinderblock or lava and the like. However, in principle, porous metallic orother porous materials, such as sintered metallic compositions, whichcan physically and chemically withstand the hot fuel, hot air and hotmixtures of fuel and air in the carburetor, are also suitable.

The injecting means are typically nozzles or jets which spray the fuel.Complicated systems of pumps and injectors common in conventional fuelinjection systems and complicated structures common in conventionalcarburetors are avoided. In the present invention, two injecting meanscan suffice for a six or eight cylinder engine and a single injectingmeans can suffice for a four cylinder engine.

According to the present invention, the fuel is preferably heated to anat least partially vaporized condition before being injected. To thisend there may be provided a heat exchanger in which heat is transferredfrom the hot exhaust gases or from the hot engine coolant to the fuel.For example, the heat exchanger may be in the form of a shell, i.e., avessel, through which hot exhaust gases or the hot coolant is passed anda coil-shaped segment of the fuel line in the shell. Likewise for thepurpose of helping to assure complete vaporization of the fuel, the hotexhaust gases or the hot coolant may also be conducted through means fortransferring heat from the hot exhaust gases or the hot coolant to thecarburetor housing and the porous matter contained therein. Transfer ofheat from hot coolant to the housing and porous matter in the housingand/or to the fuel line is, in general, practically effective only ifthe engine coolant is water or other liquid and not if the enginecoolant is air. It is optional to provide auxiliary electricalresistance heating means for the fuel line and/or for the carburetor toaugment any heating provided by the exhaust gases or by the coolantbefore the exhaust gases or the coolant have reached their respectivenormal temperatures during operation of the engine. Such heating meansmay be thermostatically controlled to be turned off once the exhaustgases or the coolant have been fully heated.

In the most preferred embodiment of the present invention, in which theefficiency of engine operation, practicality, and adaptability of theinvention are the greatest, the aforementioned heating of the fuel, thehousing and the porous matter contained in the housing are effectedsolely by means for transferring heat from the exhaust gases to the fuelline and to the housing and the porous matter contained therein. Amongthe advantages of this arrangement are the applicability thereof to anair-cooled engine as well as to a liquid cooled engine. Anotheradvantage of this arrangement is that once the engine has reached itsnormal operating temperature, sufficient heat can readily be transferredfrom the exhaust gases to the fuel line to assure that the fuel is in asubstantially completely vaporized state when it is injected into thehousing. The relatively cooler air which is drawn into the housing maycause some of the vaporized fuel to condense. However, the means fortransferring heat from the exhaust gases to the housing and the porousmatter assure revaporization of any condensed fuel. Preferably, theexhaust gases are tapped off from the exhaust manifold, utilized topreheat the fuel by means of the aforementioned type of heat exchangeror equivalent thereof and then conducted to means for transferring heatfrom the hot exhaust gases to the housing and the porous mattercontained therein. The housing includes a base, and the means fortransferring heat from the exhaust gases to the housing and the porousmatter contained therein preferably comprises passages formed in thebase for the conducting of the exhaust gases therethrough.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be further described by reference to specificembodiments as illustrated in the drawings, in which:

FIG. 1 is a cross section of an embodiment of a carburetor according tothe invention;

FIG. 2 is a like cross section of a portion of another embodiment of acarburetor according to the invention;

FIG. 3 is a plan view of the top face of one of the elements of theembodiment of FIG. 2;

FIG. 4 is a plan view of the bottom face of the element of FIG. 3;

FIG. 5 is a plan view of the top face of another element of theembodiment of FIG. 2;

FIG. 6 is a plan view of the bottom face of the element of FIG. 5; and

FIG. 7 is an elevation, partly in cross section, of another arrangementaccording to the invention, utilizing the carburetor of FIGS. 3 - 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The carburetor 10 is in the form of a housing having a cylindrical sidewall 11 provided with upper and lower closures 12 and 13.

Communicating with an inlet opening in the upper portion of the wall 11is an air intake nipple 14. A screen 15 is provided across the inletopening for filtering out particulate matter. A butterfly valve 16 isarranged in the air intake nipple 14. The distal end of the intakenipple 14 is connected to an air intake pipe 17.

Communicating with an outlet opening in the lower closure 13 is anoutlet nipple 18. A screen 19 is provided across the outlet opening forretaining in the housing the hereinafter described matter whilepermitting the mixture of vaporized gasoline and air formed in thecarburetor to discharge. A butterfly valve 20 is arranged in the outletnipple 18. The distal end of the outlet nipple 18 communicates with theintake manifold of the engine, which is not illustrated.

The fuel line 21 communicates with a pair of conventional fuel injectors22 and 23 which are received in respective openings in the upper closure12. The tips of the injectors project slightly into the housing 11. Theinjectors 22 and 23 are connected to the electrical system of the motorvehicle (not illustrated) by means of conventional electrical connectors22a and 23a, respectively.

The housing is substantially filled by an upper bed of small porousceramic pieces P and a lower bed of smaller porous ceramic particles P'.

An optional feature of the invention is auxiliary heating means for thefuel being fed to the injectors 22 and 23 through the fuel line 21 andfor the ceramic material in the housing. A heat exchanger 24 is providedhaving a cylindrical shell 25 communicating with the interior of whichthrough one end wall 26 thereof is an inlet pipe 27 and communicatingwith the interior of which through the opposite end wall 28 thereof isan outlet pipe 29, the outlet pipe 29 being of smaller internal diameterthan the inlet pipe 27. A portion of the fuel line 21 is formed into ahelical coil 21a which is inside and substantially coaxial with theshell 25 and the inlet end of which is fed by the entering of the fuelline 21 into the shell 25 at an opening 25a in the shell 25 near the endwall 26 and the outlet end of which communicates with the portion of thefuel line 21 passing out of the shell 25 at an opening 25b in the shell25. The inlet pipe 27 connects the shell 25 to the conventional coolingsystem of the motor vehicle (not illustrated) and, in particular, to theline carrying the fluid coolant, typically water or an aqueous solutionof a conventional organic water freezing point depressant and boilingpoint elevator. For convenience, the coolant will hereinafter bereferred to as "water." A portion 29a of the outlet pipe 29 passesdiametrically across the interior of the housing, entering and leavingthe housing through a pair of respective openings provided in the wall11 for the purpose. An electrical heating coil 30 is helically wrappedaround pipe portion 29a and is connected to an electrical connector 31which passes through the wall 11, the connector 31 being connected tothe conventional electrical system of the motor vehicle (notillustrated) whereby the coil 30 receives power from the electricalsystem. Alternatively, as illustrated in phantom, an electrical heatingcoil 30' is helically wrapped around a portion of the fuel line 21 nearthe injectors 22 and 23 and is connected to an electrical connector 31'which is connected to the conventional electrical system of the motorvehicle whereby the coil 30' receives power from the electrical system.The fuel line 21 is covered with thermal insulation (not illustrated)which covers the exterior of the coil 30' as well, the connector 31' ofcourse penetrating through or being totally outside the insulation topermit the necessary connection to the electrical system of the motorvehicle.

When the ignition is switched on, fuel is pumped through the line 21 tothe injectors 22 and 23 which alternately inject the fuel onto theporous ceramic pieces P. Two injectors are usually necessary to providean adequate fuel supply for a six or eight cylinder engine whereas oneinjector may be adequate for a four cylinder engine. The ceramic piecesP, particularly due to their porosity, cause the fuel to be distributedover a large surface area, resulting in essentially completevaporization of the fuel, particularly once the engine has warmed up.Some of the fuel may not vaporize on the ceramic pieces P but trickledown through the ceramic pieces P and onto the ceramic particles P'.These, too, are porous and, due to being smaller than the pieces P, havean even larger specific surface area, facilitating vaporization of thefuel which theretofore had not vaporized.

Before the engine reaches its normal elevated operating temperature,typically 175°-185° F, at which vaporization of the fuel occurs morereadily, supplemental heating of the carburetor to facilitatevaporization of the fuel may be desirable. Moreover, even after theengine has reached its normal elevated operating temperature, it may bedesirable to provide supplemental heating of the carburetor to assurethat the engine heat is effectively transferred to the ceramic piecesand particles on which the completion of vaporization of the fuel orrevaporization of fuel which has condensed is to take place. Also tohelp assure complete vaporization of the fuel, means may be provided forpreheating the fuel before it enters the carburetor. Means for effectingall of the foregoing are provided in the exemplary embodimentillustrated herein. The engine's cooling water is fed through the shell25 of the heat exchanger 24. Because the outlet pipe 29 from the shell25 is of smaller diameter than the inlet pipe 27 to the shell 25, it issimple to design the dimensions of the system so that at steady state,the shell 25 remains filled with circulating cooling water. Once theengine is warmed up, the cooling water will be hot and will heat thefuel flowing through the coil 21a in the shell 25. Hence, the fuel willbe injected into the carburetor housing in a pre-heated, partiallyvaporized condition. Typically, the fuel is gasoline and the pre-heatingis to a temperature of about 175° to about 185° F. Also, because thepipe portion 29a is an extension of the outlet pipe 29, hot water willflow through it, too, and help heat the ceramic material in thecarburetor housing typically to a temperature of about 175° F.,particularly the ceramic particles in contact with or adjacent the pipeportion 29a. The electrical heating coil 30 can be used to provide moreeffective supplemental heating of the ceramic material during theinitial period of operation of the engine before the engine has reachedits normal elevated operating temperature. In particular, the heatingcoil 30 may be thermostatically controlled so that it is on only whenthe engine is below its normal operating temperature. Alternatively, itmay be preferable that the heating coil be used instead to pre-heat thefuel outside the carburetor, to avoid any possibility of combustionoccurring in the carburetor, though the ceramic particles are generallyeffective to keep fuel vapors from contacting the coil in suchquantities as would present a critical combustion hazard. Again the coilwould preferably be thermostatically controlled so that it is on onlywhen the engine is below its normal operating temperature. Thealternative location is illustrated in phantom as heating coil 30' withits electrical connector 31', the heating coil 30' preferably beinghelically wrapped around a portion of the fuel line 21 closely adjacentthe injectors 22 and 23 so that essentially no heat is lost by the fuelbefore it is injected. Typically, the thermostat for heating coil 30 or30' is set to turn the coil off at an engine, i.e., engine coolant,temperature of 175° F.

The admission of air through the air intake pipe 17 and the air intakenipple 14 to the carburetor housing is regulated by the butterfly valve16 in the air intake nipple 14. The screen 15 filters particulate matterout of the air before the air enters the carburetor housing. The flow ofthe mixture of air and vaporized fuel formed in the carburetor housingfrom the carburetor housing to the intake manifold of the engine iscontrolled by a butterfly valve 20 in the outlet nipple 18 to which theintake manifold is connected. The screen 19 prevents the ceramicmaterial from being blown out of the carburetor housing. The butterflyvalves 16 and 20 are controlled by simple throttle linkages which openthe butterfly valve 20 slightly before the butterfly valve 16 in orderto allow free passage of the fuel-air mixture into the intake manifoldas the mixture is formed. The further the operator of the motor vehicledepresses the accelerator pedal, the greater the rate at which fuel isinjected by the injectors 22 and 23 and the further the valves 16 and 20open whereby the rate at which the mixture of air and vaporized fuel isformed is progressively increased. Even when the valves 16 and 20 areclosed, that is, when the accelerator pedal is not at all depressed, thevalves 16 and 20 do not completely close off the air intake nipple 14and the fuel-air mixture outlet nipple 18 so that the engine may bestarted up without necessarily depressing the accelerator pedal. Inbench tests using a standard automobile engine at 1,200 r.p.m., thiscarburetor of the invention used as little as a third the amount of fuelconsumed with the use of a standard carburetor.

With reference to the embodiment of FIGS. 2 - 6, the lower closure 13and screen 19, which constitute the base of the carburetor housing andthe nipple 18 in which the butterfly valve 20 is mounted, are replacedby means 40 for transferring heat from exhaust gases of the engine tothe housing and the porous matter contained in the housing, and a baseplate 13' in which the butterfly valve 20 is mounted. The heat exchanger24, the inlet pipe 27 thereto, the outlet pipe 29 therefrom and thecoils 30 and 30' and electrical connectors 31 and 31' are dispensedwith.

The heat transfer means 40 consists of a plate 41 and a screening plate42 supported by the plate 41. Machined on the top face of the screeningplate 42 are a plurality of concentric circular ribs 42a separated by aplurality of concentric circular flats 42b. Drilled through the flats42b are a plurality of pin holes 42c which do not permit passage of eventhe finer porous matter in the housing. Machined on the periphery of thebottom face of the screening plate 42 is an annular lip 42d, which formsa plenum chamber 42e between the bottom face of the screening plate 42and the top face of the plate 41, the plenum chamber 42e communicatingwith the outlet opening formed through the center of the plate 41.

The plate 41 is constituted of an elevated disc 41a machined on a flatsquare base 41b. For conducting hot exhaust gases from the engine aredrilled channels 41c, 41d, 41e and 41f in the disc 41a, having anexhaust gas inlet 41g on the cylindrical side wall of the disc 41a andan exhaust gas outlet 41h on the bottom face of the plate 41. A set ofholes 41i is drilled through the plate 41 in a circular array adjacentthe periphery of the disc 41a to receive screws (not illustrated) forfastening the plate 41 to the cylindrical side wall 11 of the housing,which is provided with threaded-holes (not illustrated) for receivingthe screws. Near each corner of the plate 41 is drilled a hole 41j whichmay be used to receive bolts or screws for mounting of the base 41 ontoother structures (not illustrated) if desired. The base plate 13' isattached to the plate 41 by such means as screws (not illustrated).Drilled in the base plate 13' is a channel 41k. The inlet end of thechannel 41k is an opening 41m in the upper face of the plate 13' whichis in alignment with the exhaust gas outlet 41h on the lower face of theplate 41. The outlet end of the channel 41k is an opening 41n below thebutterfly valve 20 in the wall of the central bore 13a' of the plate 13'in which the butterfly valve 20 is mounted.

A very minor proportion of the exhaust gases are tapped off the exhaustmanifold and conducted by conduit means to the inlet opening 41g of theplate 41. The exhaust gases flow through the channels 41f, 41c, 41d and41e, pass from the exhaust gas outlet 41h in the plate 41 into theexhaust gas inlet 41m in the plate 13', flow through the channel 41k andexit through the outlet opening 41n into the bore 13a', where theexhaust gases mix with the mixture of fuel and air about to enter theintake manifold from the carburetor of the invention. Because theopening 41n is located downstream from the butterfly valve 20, thenormal suction in the intake manifold during operation of the enginewill serve to efficiently draw the exhaust gases through the pathhereinabove described. Heat from the exhaust gases heats the disc 41awhich, in turn, heats the cylindrical side wall 11 and the porousmatter. Moreover, any unvaporized droplets of liquid fuel in the mixtureof air and fuel which passes through the holes in the screening plate 42will be vaporized in the plenum chamber 42e and on the top surface ofthe heated disc 41a.

In the embodiment of FIG. 7, which is the most preferred embodiment, theexact same reference numbers are used where the parts are exactly thesame as in a heretofore described embodiment in such cases, it is notconsidered necessary to specifically refer to the parts again. Here, thecarburetor itself, including the heat transfer means 40 incorporated inthe base thereof, is structurally and functionally exactly the same asin the embodiment of FIGS. 2 - 6. To the shell 25' of the heat exchanger24' are fed hot exhaust gases from the exhaust manifold 45. The exhaustmanifold 45 communicates with the shell 25' by means of a pipe 44 whichcommunicates with the interior of the exhaust manifold through a wall ofthe exhaust manifold, an inlet pipe 27' for the shell 25' whichcommunicates with the interior of the shell 25' through an end wall 26'of the shell 25', and a coupling 43 which connects together the pipes27' and 44. The coupling 43 is conventional. The ends of the pipes 27'and 44 are externally threaded and the coupling 43 is internallythreaded, so that the pipes 27' and 44 can be connected and disconnectedmerely by rotating the coupling 43. Communicating with the interior ofthe shell 25' through the other end wall 28' thereof is an outlet pipe29' of smaller internal diameter than the inlet pipe 27'. The downstreamend portion 29a' of the pipe 29' is connected to the exhaust gas inlet41g in the disc 41a in the carburetor housing, an opening (notillustrated) being provided in the cylindrical wall 11 of the housingfor passage therethrough of the pipe end portion 29a'. It can thus beseen that in this embodiment, the exhaust gases are used both topre-heat the fuel and to heat the carburetor housing and the porousmatter in the carburetor housing. The exhaust gases are so hot thatpre-heating of the fuel by means thereof results in the fuel beingsubstantially completely vaporized when it enters the housing. The meansfor transferring heat from the exhaust gases to the porous matter andthe interior of the housing assure, again because of the intense heat ofthe exhaust gases, particularly fast vaporization of any unvaporizedfuel and revaporization of any vaporized fuel which has condensed.

While in the drawings the fuel injectors have been illustrated aspassing through the upper closure 12 of the carburetor, it is just aswell to have the injectors communicate with the interior of the housingthrough the side wall 11. As is apparent from the foregoing descriptionof the invention, the means for injecting the fuel need not be fuelinjectors, which deliver the fuel in pulses. When electrical fuelinjectors, as illustrated in the drawings, were intentionally shortedout so that the injectors became mere nozzles from which the fuelsprayed continuously during operation of the engine, the performance ofthe carburetor of the invention did not suffer. Hence, the means forinjecting the fuel in the present invention may be any nozzles or jetsor like means. In the embodiments of FIGS. 2 - 7, the means at the baseof the housing 10 for heating the porous matter and the interior of thehousing 10 need not be of the particular construction herein illustratedbut may simply be functionally equivalent thereto. For example, theplate 41 may be dispensed with, the plate 13' used itself as the closurefor the bottom of the housing 10, a screen such as screen 19 of theembodiment of FIG. 1 arranged across the mouth of the bore 13a' and aflat spiral coil of highly heat conductive tubing, such as copper tubingarranged over the plate 13' in place of the plate 41. The outer end ofthe heating coil is connected through an opening in the housing wall 11with the conduit 29', and the inner end of the heating coil is connectedto the exhaust gas inlet opening in the plate 13'. The foregoing and allother modifications and variations utilizing the principles of thepresent invention are intended to be encompassed by the hereto appendedclaims.

What I claim is:
 1. A carburetor for supplying a fuel/air mixture to aninternal combustion engine having an intake manifold comprising ahousing, contained in the housing only matter which is inert relative tothe fuel, said matter being porous, means for injecting fuel into thehousing and onto said porous matter, means for transferring sufficientheat from the exhaust gases of the engine to the fuel before the fuel isinjected into the housing and means for transferring sufficient heat tothe housing and the porous matter so that all the fuel is completelyvaporized when it leaves the housing, means for admitting air into thehousing simultaneously with the injection of the fuel to form a mixturewith all the vaporized fuel and means for conducting the entire mixtureout of the housing directly to the intake manifold during all phases ofoperation of the engine, for combustion in the engine.
 2. A carburetoraccording to claim 1 in combination with a fuel line communicating withthe fuel injecting means and in which the means for transferring heatfrom the exhaust gases to the fuel comprises a vessel, means forconducting the exhaust gases through the vessel, and a portion of thefuel line passing through the vessel.
 3. A carburetor according to claim2 for an internal combustion engine having an exhaust manifold,comprising first conduit means communicating at one end with said vesseland adapted to communicate at the other end with the exhaust manifoldand second conduit means communicating at one end with said vessel at apoint remote from the communication of the first conduit means with saidvessel and communicating at the other end with said means fortransferring heat from the exhaust gases to the housing and the porousmatter.
 4. A carburetor according to claim 3, in which the housingincludes a base and the means for transferring heat from the exhaustgases to the housing and the porous matter comprises passages formed inthe base for the conducting of the exhaust gases therethough.